Although the use of intervertebral spacers is widespread in spine surgery, they present a notable challenge. On the one hand, maximizing the amount of surface area of the spacer would appear to better distribute their loads prevailed upon the adjacent vertebral body endplates. On the other hand, maximizing the amount of space preserved for blood and bone graft material would appear to improve the quality and rate of biologic bone growth for fusion and healing. Currently, a tradeoff has been realized in conventional spacers through minimizing the wall thickness of cages to allow for inserted or packed graft or bone growth factor materials. However, this tradeoff may not only predispose the cage to subsidence, it also leads to spacers that are very wide in relation to the available surgical access trajectories, thereby minimizing the margin of safety during their approach.
U.S. Pat. Nos. 5,665,122; 7,879,098 and 6,723,126 each discloses a different multi-piece, expandable fusion cage.
U.S. Pat. No. 6,193,757 discloses a unitary expandable fusion cage having a pair of flanges flexibly connected on one end and pointing towards each other at the other end.
US Published Patent Application 2004-0002760 discloses a flexible device having a pair of flanges flexibly connected on one end and made of bone.
US Published Patent Application 2012-0089231 discloses a unitary expandable fusion cage having a pair of flanges connected on one end and pointing towards each other at the other end.
US Published Patent Application 2009-0099610 and PCT Published Patent Application WO2007-078692 each discloses an expandable stent-like device.
US Published Patent Application US2002-0007218 discloses a Y-shaped device.